The subject matter disclosed herein relates in general to the initiation of devices located on vehicles (e.g., spacecraft, launch vehicle, etc.), and in particular to systems configured to control the initiation of non-energetic and/or energetic hold-then-separate devices located on the vehicle.
Launch vehicles typically have multiple stages and are used to carry payloads during travel away from the Earth's surface after the vehicles are launched, and then place or deploy the payloads into orbit or beyond. These payloads are commonly referred to as satellites if they are intended to orbit a body (e.g., Earth) after deployment, or as spacecraft if they are intended to leave the Earth's orbit after deployment. The term “space payload” will be used herein to refer to both satellites, spacecraft, and/or space-bound vehicles, devices, and/or structures and other payloads.
Space payloads typically utilize hold-down and release mechanisms (“HDRMs”) (i.e., a “hold-then-separate” device) to securely hold, retain, or stow elements of the space payload during launch. Elements of space payloads may include, but are not limited to, solar arrays, antenna reflectors, radiators, instrument booms, propulsion pointing actuators, doors, sensors, or other deployable devices, etc. and/or deployable components or systems (e.g., satellites, micro-satellites, etc.). The elements may be deployed as desired by activating the hold-down and release mechanisms. As will be appreciated by those of skill in the art, deployable elements may include parts of spacecraft (e.g., deployable from the spacecraft) and spacecraft as the deployable element (e.g., as deployed from a launch vehicle or stage of a launch vehicle).
An HDRM is generally an electro-mechanical device, and in some configurations may be a “one-shot” device. In such “one-shot” configurations, after the HDRM is activated to release a stowed or held element, the HDRM either needs to be replaced, refurbished, or reset—depending on the type of technology that the HDRM employs. An HDRM is typically not a motorized device or other type of device that will return to its original state without some type of external intervention.
HDRMs are generally broadly categorized into three different types: explosive, pyrotechnic, and non-explosive—depending upon the type of activation or actuation mechanism utilized. Explosive and pyrotechnic HDRMs are also both typically referred to as energetic HDRMs, while a non-explosive HDRM or a non-pyrotechnic HDRM is also typically referred to as a non-energetic HDRM. An explosive HDRM has an activation mechanism that detonates on command, while a pyrotechnic HDRM has an activation mechanism that burns or deflagrates on command. A non-energetic HDRM is one that typically utilizes an activation mechanism such as a fuse wire or link wire that heats and weakens on command from a control unit when an amount of electrical current passes through the wire, thereby causing it to melt and break. Other types of non-energetic HDRMs utilize a shape memory alloy or utilize the volumetric expansion of certain materials, such as paraffin, when changing from solid to liquid phase. For simplicity, the discussion herein will focus on the fuse wire or link wire style non-energetic HDRMs, but it can be seen that embodiments of the present disclosure described herein would be applicable to all types of non-energetic HDRMs.
In a particular type of non-energetic HDRM, when a fuse wire breaks, a release wire that is wrapped around and thereby enclosing two parts or halves of a cylindrical split-spool assembly is released. The separation of the cylindrical split-spool assembly allows for movement of a pre-loaded device (e.g., a bolt) attached to the split-spool assembly. Release of the bolt subsequently releases a stowed element of the space payload or release of a payload entirely (e.g., satellite/micro-satellite from a launch vehicle or stage of a launch vehicle and/or released from another satellite). This type of non-energetic HDRM is commonly referred to as a split-spool release device (“SSRD”). Other common types of non-energetic HDRMs are commercially available.
In the relevant art, the relatively broad combination of a control unit, a plurality of energetic devices, and an interface bus through which signals (e.g., power and data) are sent and received as between the control unit or controller and the energetic devices (i.e., two-way communication) is generally referred to as a “networked initiation system.” It is a distributed type architecture in which the various components (e.g., the control unit and the energetic devices) are located at different places on the space payload (and/or launch vehicle) and are all connected by the interface bus. This limitation in the number of communication channels limited the number of payloads that could be deployed from the spacecraft.
Networked initiation systems are known that are used strictly with various types of energetic devices. What is needed is a networked initiation system having the features described herein.